Watering in the Morning

Moist conditions encourage fungal infection, so watering your trees properly is key to preventing this type of disease. Water early in the morning, which gives bark and leaves plenty of time to dry before nightfall. Also, try not to wet the bark if you can help it.

Pruning with Care

Bark helps protect shrubs and trees against fungi, but pruning wounds are susceptible to infection. To avoid this, prune evergreens and spring-flowering plants in the late dormant season. This allows pruning wounds to heal when warm weather arrives in spring, avoiding the cold, damp winter when fungal disease can run rampant. Prune young trees regularly and properly by making cuts outside the branch bark ridge and remove dead or broken limbs. This can prevent the need for major pruning when trees are older and more susceptible to wood decay. And even if you don't think your trees are infected, clean pruning tools before using them and between each cut to avoid spreading disease.

Nourishing Your Plants

Weak plants are more vulnerable to diseases than healthy plants, which makes proper care vital. For instance, frost damage, drought and lack of nutrients make trees particularly susceptible to canker diseases. Unless your climate is damp, water trees every week during the summer to prevent them from drying out, and maintain a regular fertilizing schedule to encourage healthy growth. If you experience freezing temperatures in winter, you may need to wrap cold-intolerant trees to prevent frost damage.

Treating Fungal Diseases

If fungus has already destroyed parts of a tree, you may be able to prevent it from spreading to the rest of the bark with fungicide. Rather than spray a general fungicide and cross your fingers that it works, carefully diagnose the fungal infection and use a spray made specifically to treat it. You may need a professional assessment for diagnosis. After the initial application to coat the surface of your tree, keep up the barrier with follow-up applications, especially when you spot new growths that need protection. Also, keep in mind that fungicides are rarely effective against canker diseases, which require pruning and proper care instead.